It is known, for instance from U.S. Pat. No. 5,165,353 of J. Freermann, to form a selvedge in the longitudinal pile-free edge strip of a piece of textile goods by moving the goods longitudinally in a transport direction through four folding stations and then through a sewing station. In the first folding station the outer two-thirds of the edge strip are folded up into a vertical position while the inner third of the edge strip is maintained flat and horizontal so that the edge strip is basically of L-section. Then in the second folding station the outer third of the edge strip is folded inward to a horizontal position while maintaining the inner third flat and horizontal and the middle third upright so that the edge strip is basically of C-section. In the third folding station the outer third of the edge strip is folded down to a vertical position next to and continuous with the middle third while the inner third is maintained flat and horizontal and the middle third is upright. In the fourth folding station the outer and middle thirds of the edge strip are folded together down to a horizontal position atop the inner third while maintaining the inner third flat and horizontal. In the sewing station a sewing machine stitches vertically through the inner, middle, and outer thirds of the triple-folded edge strip to stabilize it. The piece of goods is engaged by gripping a strip of it parallel to but offset from the edge being selvedged, the edge being entrained by moving this gripped strip.
A similar system is described in U.S. Pat. No. 3,486,470 of R. Florczak. Here the edge is similarly folded inward, but the piece of goods is moved in part by gripping the edge with rollers that also serve to fold the edge. The rollers of each folding station are all identical and are all driven by a common drive chain so that they all move synchronously at the same peripheral speed.
The problem with these systems is that the edge to be selvedged is frequently somewhat out of square, that is as a result of handling and construction the edge is somewhat longer or shorter than the piece of goods. The most common situation occurs when the edge is somewhat longer than the goods so that the leading and trailing corners form outwardly projecting points. When such an overlong edge is folded over and stitched it produces an unacceptable bump or projection at both the trailing and leading ends This problem is particularly evident in the case of terry cloth where the edge is a pile-free zone that with handling can get somewhat longer than the body of the piece which has pile.